coolrcdad: I'm not currently using any ceramic nitride diff and thrust balls on my newly built FTTC3...but before I made the switch to the TC3 from and HPI Pro2, i was using Acer's ceramic nitride diff and thrust balls. All I can say is that the ceramic nitride balls are very durable and diff action was on the SPOT!.
The only downside is the cost. Only rebuildt my pro2 diffs once and that was after putting in the ceramic nitride balls. I plan on running them, but not at the moment. Need to save up!
By the way, I run in parking lot tracks. Hope this helps.